I have a user Form that has several Text Boxes & Combo Boxes. From this Form
I want the user to Input Data and have it placed through out the rest of the
workbook.

I got the User Form to show up when you click a cell on the worksheet, but
for some reason it shows up as a seperate screen and not as sheet 1. The name
of the sheet I want it as is named "Data Input".

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
UserForm1.Show
End Sub

How can I get the Text and Combo Box on the user form to to fill in the
worsheet. Also How can I added the different choices to the combo box?

I tried, but it did not work for some reason.

With UserForm1.ComboBox1
.AddItem "a"
.AddItem "b"
.AddItem "co"
End With